As known, ethylene production of plant tissues increases upon the effect of cold, physical or chemical damages and microbial or insect infections (plants 120, 63-69 1974). In general, it can be laid down as a fact that plants react with increased ethylene production to all environmental factors affecting their normal development, such as meteorological effects (heat, rain, fog, frost, wind, intense radiation, etc.), chemical effects (effects of herbicides, agricultural chemicals, etc.), and damage caused by microorganisms and animals (such as insects, mites, rodents, etc.). These factors are termed in the following as stress factors. Ethylene overproduction leads to the disintegration of the semipermeable lipid-polysaccharide double walls of membranes and cells, which involves the premature ageing of plant cells and tissues, whereupon the vegetation period decreases and/or the metabolism slows down (Plant Physiol. 68, 594-596 1981). Ethylene production involves a decrease in cell protein and RNS content (Plant Physiol. 69, 385-388 1982). Upon ethylene overproduction provoked by stress factors the plant cells collapse energetically, which necessarily leads to a decrease in yield. Such a decrease in yield may appear e.g. as a loss in crop yield, stunting, slow growth, anamorphosis, etc.